Devices that make possible, at the end of the imaging beam path, a selective detection of individual spectral components of the detected light are often provided in microscopy, in particular confocal microscopy. Beam splitters are often used for this; these transmit a specific spectral component of the light while reflecting the other spectral components. The result is that, for example, the fluorescent radiation emitted from a sample being imaged can be selectively detected.
An alternative possibility for selective light detection is to pass the detected light firstly through a dispersing optical element, e.g. a prism, which refracts the detected light in wavelength-dependent fashion and thereby generates a spectrally dispersed, diverging light bundle. This light bundle is then delivered to a mirror slider apparatus that is constituted from multiple cascades of mirrors. Each of these mirror cascades is made up of two mirror elements that are separated from one another by a gap. A portion of the spectrally split light bundle passes through this gap, while the remaining portion of the light bundle is reflected at the mirror elements onto a further mirror cascade that in turn directs a specific spectral component onto another detector.
A mirror slider apparatus of this kind has the advantage, as compared with the beam splitters predominantly used in the existing art, that the spectral components to be delivered to the detectors can be modified in simple fashion by shifting the mirror elements. Examples of a mirror slider apparatus of this kind are described in DE 43 30 347 A1 and in DE 100 38 049 A1.
The mirror slider apparatuses have the disadvantage, however, that they are of comparatively complex construction in order to enable the desired flexibility in selecting the spectral light components to be detected. Precisely operating motors are therefore required in order to move the mirror elements into the respectively desired position. Displacement of the mirror elements is moreover comparatively time-consuming.
U.S. Pat. No. 6,396,053 B1 discloses a scanning microscope that contains a light deflection device that delivers the spectral components of a light bundle, spectrally dispersed by a prism, selectably to different detectors. This light deflection device encompasses a micromechanical mirror arrangement having a plurality of mirror actuators that can move individually into different reflection positions. For example, five different reflection positions, and thus five different deflection angles, are provided for each of these mirror actuators, in order to direct the light selectably onto the different detectors. This comparatively large number of different reflection positions that each individual mirror actuator can assume requires precise application of control to the respective mirror actuator; technical implementation of this previously known light deflection device is thereby made difficult.
Regarding the existing art, reference is furthermore made to so-called digital light processing (DLP) systems, which are utilized in projection technology, for example, for video projectors. These DLP systems likewise encompass a micromechanical mirror arrangement having a plurality of mirror actuators arranged in the form of a matrix. For each of these mirror actuators, however, provision is made only for exactly two reflection positions, between which the mirror actuator can move back and forth up to several thousand times per second. Each mirror actuator can represent one image point or pixel, the brightness of which is adjusted over the entire time during which the respective mirror actuator is located, within a predetermined time interval, in the one or the other reflection position.
Because of the short switching times, it would be desirable also to use the DLP technology explained above, for example, in confocal microscopy in order to deflect detected light onto different detectors. The only way to implement these short switching times, however, is by providing only exactly two defined reflection positions, which ultimately also make possible only two different deflection directions. In typical confocal applications, however, the deflection of light in more than two directions is desirable.